Current weather 22f/54% humidity, high today 40f
Greenhouse 50f/75% humidity (14x24x10ft) too tall, heating with 155,000BTU diesel shop heater

Forecasters said it would be 27f, they lied, LOL, they really don't know much about forecasting cold weather down here.

Hope to maintain nighttime 50f all winter, I would like 40f, but I can't seem to get thermostat to cooperate.  I intend to build solar heater for daytime heating, probably will not get done this winter.

EDIT-
I would like to hear from those that have greenhouses/high/low tunnels on how they are heating and what kind of temperature/humidity you are experiencing.  The sizes would also be interesting.

I thought Texas was supposed to be hot!?!? We're getting that kind of cold in Toronto!

Keep yourself and the figs warm my friend

Can you explain a solar heater for a greenhouse?

In winter my greenhouse would hit 120F if not ventillated. Most days the exhaust fans run from 9am to 5pm. That's when it's on chill cycle. After chilling is complete, about Xmas, the fans run slightly less. Sometimes I even need the evaporative cooler/wet wall. On chill cycle the wet wall even runs some at night in order to hold 40-45F.

We've had very strange weather the last two wks and I thought the NWS did a good job over here. We went 36 hrs with only 3F temperature variance, 37-40F. Very unusual in west Texas. Then with these last two cold fronts they correctly predicted that the first would hold off just to the east of us. That's also very unusual. This last front did the usual, covered all of the state.

Texas is hot, in places.  From my house, which 2 miles west of the Louisiana border, to El Paso, the western border is 805 miles.  North to south Texas in right at 1000 miles, so we have a very diverse climate.

My greenhouse is partially shaded, intentionally, I use it as a shade house in summer.  I may have those temperatures in the summer, I did not have it fully erected in the summer.  I did install fans and have 36" high operable doors going full length on both sides.  I really don't think I will need the solar heaters very often, I am really building the solar system as an experiment.  I really have not figured out what I am doing, LOL.

Right now it is 27f outside and 68f in the greenhouse.

That's chilly!

It's 6°F here, rising from -8 and headed to a smashing high of 11°F